Inflatable barrier for converting a paper manufacture cylinder machine from conventional to dry vat operation and vice versa



May 24, 1966 R. E. BOWEN 3,252,854

INFLATABLE BARRIER FOR CONVERTING A PAPER MANUFACTURE CYLINDER MACHINE FROM CONVENTIONAL TO DRY VAT OPERATION AND VICE VERSA Flled May lO, 1963 5 Sheets-Sheet l May 24, 1966 R. E. BOWEN 3,252,854

INELATABLE BARRIER FOR CONVERTING A PAPER MANUFACTURE CYLINDER MACHINE FROM CONVENTIONAL TO DRY VAT OPERATION AND VICE VERSA Filed May lO, 1965 3 Sheets-Sheet 2 May 24, 1966 i R. E. BOWEN 3,252,854

INFLATABLE BARRIER FOR CONVERTING A PAPER MANUFACTURE CYLINDER MACHINE FROM CONVENTIONAL TO DRY VAT OPERATION AND VICE VERSA Filed May l0, 1965 5 Sheets-Sheet 5 United States Patent O 3,252,854 INFLATABLE BARRIER FOR CNVERTENG A PA- PER MANUFACTURE CYLINDER MACCHINE FROM CONVEN'HUNAL T0 DRY VAT OPERA- TION AND VICE VERSA Robert E. lllowen, Alton, Ill., assignor, by mesne assignments, to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed May 10, 1963, Ser. No. 279,393

Claims. (Cl. 162321) l This invention relates generally to the manufacture of paper or paperboard on a so-called cylinder machine, or the like, and particularly to such manufacture when characterized by a dry or restricted vat.

The so-called cylinder machine has long been utilized in the manufacture of paper and paperboard. Such a machine consists essentially of a cylinder mold arranged for rotation with a substantial part of its circumeference-conventionally 50 to 75%-submerged in a pool of paper stock. The circumferential area of the cylinder mold consists of a forming wire, which is a reticulated surface through which White water may be drawn from the paper stock in the pool to deposit a layer of fibers on the forming wire as the cylinder mold rotates within the pool. Suction is usually applied to the interior of the cylinder mold so as to draw the stock toward the forming wire, and to extract white Water from the fibers deposited on the forming wire. The layer of bers deposited on the forming wire is then removed from the cylinder mold at an area thereof which is outside the pool of stock in which the cylinder mold is partially submerged. The removal of the layer of bers from the cylinder mold is usually accomplished by couching them olf on to a felt traveling substantially tangentially of the cylinder mold.

As indicated above, in the conventional cylinder mold operation, the pool of stock surrounds somewhat less than all of the peripheral area of the forming wire, and the pool is maintained thereabout by a suitable vat, the confining walls of the pool being substantially spaced from the forming wire. It has long been known, however, that, under some circumstances, it is advantageous to so restrict the peripheral extent of the stock pool that it will embrace a much smaller fraction of the forming Wire periphery. When such restriction is limited to the peripheral area of the forming wire substantially less than 180 from the couching position, but on the side of the cylinder mold which is approaching the couching position, little or no white water may be present in that portion of the vat circle (i.e., the space between the forming Wire and the confining wall of the vat) which is within about 180 from the couching position but on the side of the cylinder mold which is receding from the couching position; and such an operation is termed a dry vat operation. On the other hand, it is sometimes desirable to so restrict the circumferential extent of the pool of stock in the vat circle that, short of a dry vat condition, the cylinder mold is nevertheless submerged to a substantially lesser degree than in the conventional operation; and this is termed restricted vat operation.

The operation of cylinder mold processes under either dry or restricted vat conditions frequently results in the improve-ment of the quality of paper formation, and also improves the uniformity (across the paper web) with which the stock is deposited on the forming Wire and transferred to the traveling felt. Whether it is preferable in a given operation to operate under the conventional vat conditions, or to operate under dry or re- 3,252,854 Patented May 24, 1966 ice stricted vat conditions, depends upon a number of Variables, including the character of stock being deposited and the charatcer of the paper web which it is desired l to produce.

. of the vat.

In cylinder type paper machines wherein the feed box, for constantly maintaining the head of the pool of stock in the vat circle, is located on the side of the cylinder mold which is approaching7 the couching position, the operation is characterized as a counter-flow operation, whereas when the fresh stock is admitted to the vat circle other ,than at the top of the pool on the side of the cylinder mold which is approaching the couch position, the operation is, at least in part, a concurrent-flow operation. In the counter-How type of operation, where it is desired to convert -a conventional vat into a dry or restricted lvat operation, it has been customary to provide a barrier at the selected position in the vat circle, thereby to limit the extent of the stock pool in the direction away from the feed box. Such a 'barrier bridges the Vat circle at the chosen location, and is intended to prevent the flow of stock from the feed box past the barrier. Such barriers may be so arranged as to be permanently (i.e., until worn to the extent such as to require their replacement) operative, or may be selectively moved into and out of operative position. The present invention pertains to such selectively movable barriers.

In view of the fact that such barriers are intended to prevent the stock pool from extending beyond them (in a direction counter to the rotation of the cylinder mold), it is imperative to provide the best possible seal between the stationary barrier and the moving forming wire. Such a seal is customarily provided by the provision of an apron of flexible material, such as rubber or the like, biased into engagement with the forming wire throughout its axial dimension; such aprons having a flexible free end projecting from a support in the direction of the rotation of the forming wire at the point of engagement.

Since there are relatively few cylinder mold installations in which a given mold operates at all times on the same quality of stock to produce the same quality of paper or paperboard, it is desirable to equip such ma! chines so that, when and as desired, they may be operated either on a conventional basis, or on a dry or restricted Vat basis. Consequently, it has heretofore been proposed to make the barrier which bridges the vat circle, and thereby, depending upon its location, converting a conventional system into either a dry or restricted vat system, movable into and out of operative position. To accomplish, it has heretofore been proposed to provide, at the selected position in the vat circle, a movable plate hinged relative to the vat for limited rotation -about an axis parallel to the axis of the cylinder mold, so that it may be moved about such hinge axis into a position where the apron on the extremity thereof, away from the hinge axis, is either in engagement with the exterior surface of the forming wire, or in engagement with the interior confining wall of the vat. Such hinged barriers, as heretofore proposed, project away from the hinge axis in the same direction as that in which the free end of the apron projects from its support. Consequently, when such a hinged barrier is in operative position to form either a restricted or a dry vat, there is a space of triangular cross-section defined between the hinged plate and the confining wall Any vertex of such triangular space below the lip of the apron forms a pocket which provides a collecting place for the settling of sand or other adventitious material in stock, and consequently, it frequently happens that after a machine has been in operation under a dry or restricted vat condition for a substantial period of time, and it is desired to suddenly change the operation to a conventional one,'it is impossible to move the barrier out of operative position. The collection of advantitious material behind it prevents its movement with the result that the difficulties of converting the machine to the conventional operation are no less than they would have been had a stationary barrier been provided instead of a movable one. One of the objects of the present invention is, therefore, to provide a movable barrier which is free of the proclivity to become fouled in its operative position by the deposit thereabout of adventitious material.

Another object of the invention is to provide a movable barrier in which its movement between operative and inoperative positions may be accomplished almost instantaneously and without interrupting the operation of the machine.

As indicated hereinbefore, when it is desired to convert a conventional cylinder machine into a dry or restricted vat operation, the apron, which is intended to confine the circumferential extent of the stock pool, extends completely across the forming wire and rides upon it. Such a barrier, or the apron thereon, is, however, ineffective unless the vat circle beyond the ends of the forming wire is appropriately sealed. This cannot ordinarily be done by extending the aforesaid apron beyond the ends of the forming wire and into engagement with the end walls of the vat because of the irregular configuration of the sealing arrangements made between the end walls of the cylinder and the end walls of the vat. Accordingly, it is a further object of the invention to provide an effective seal beyond the ends of the aforesaid apron, and between the chimes at the opposite ends of the cylinder and the end walls of the vat, without interfering with the operation of the sealing arrangements with which the machine is normally equipped.

These and other objects of the invention are accomplished by the provision, at the chosen location in the vat circle, of a flexibly and hermetically enveloped space subject on its outside to the hydrostatic head of the stock pool above it, and subject on its inside to fluid pressure which is exteriorly controllable to move it toward and away from bridging relationship across the vat circle. In its simplest embodiment, the invention contemplates that the flexibly and hermetically enveloped space be provided by a rubber tube having closed ends. The tube may be secured in the chosen location-within the vat circle, so that the application of fluid pressure within the tube will distend it into bridging relationship between the exterior periphery of the forming wire and the interior periphery of the vat, as well as, if desired, into engagement with the chimes of the cylinder and .the sealing parts endwise beyond the forming wire. Such a tube is provided with means for controlling the fluid pressure within it from the exterior of the vat, so that it may be inflated and deflated at will, and without interrupting the continued operation of the machine.

More specifically, the invention contemplates an arrangement of the means for controlling the fluid pressure within such a flexibly and hermetically enveloped space by providing a hydrostatic head, in excess of that of the stock pool, which may be placed in communication with the interior of -the enveloped space when it is desired to have it expanded. When it is desired to contract the enveloped space, the hydrostatic head may be released,- and for quick contraction of the enveloped space, a communication between the interior thereof and atmospheric or sub-atmospheric pressure may be established. Conveniently, the aforesaid rubber tube may be provided, intermediate its length, with a large pipe connection in a position which does not interfere with the operation of the cylinder machine. The large pipe may extend, if desired, to the exterior of the vat where it is teed into a two-way valve having one connection to a large pipe discharge, and another connection to a small pipe extending upward to a level substantially above the level of the stock pool in the vat. Thus, when the valve is turned to establish communication between the small pipe and the pipe leading to the flexibly and hermetically enveloped space, a hydrostatic head above that of the stock pool is imposed on the interior of the space and it is expanded. On `the other hand, when it is desired to contract or co1- lapse the enveloped space, the valve may be turned to establish communication between the pipe leading from the enveloped space and the large pipe leading to drain. Indeed, the result may be accomplished with a one-way valve controlling only the drain, provided the drain opening through and beyond the valve is as large as the sum of the pipe providing the hydrostatic head (on the inside of the enveloped space) and the pipe leading from the interior of the enveloped space. Thereby, when the valve is closed, the high hydrostatic head (exterior to the stock pool) is imposed on the interior of the flexibly and hermetically enveloped space, but when the valve is opened, the drain accommodates both the flow from the flexibly and hermetically enveloped space and the flow from the exterior hydrostatic column, thereby quickly discharging the fluid content of the enveloped space.

From the standpoint of practical working embodiments, it is desirable to equip the membrane which envelops the above-mentioned inflatable and deflatable space with a heavy apron of rubber, or rubber-like material, comparable to that heretofore employed in connection with such barriers. In view of the constant wear upon whatever member is in constant contact with the forming wire during the operation of the machine, it is desirable to make it of heavier material than that of the flexible membrane which envelops the aforesaid inflatable and deflatable space. Accordingly, the apron above referred to may be removably attached to the membrane which envelops the aforesaid space, so that when its effectiveness begins to diminish, it may be readily replaced without disturbing the operability of the inflatable and deflatable membrane.

Furthermore, in practical embodiments, it is preferable to provide non-dellatable sealing members 'at those portions of the vat circle which are radially outward of the chimes of the cylinder mold, and the conventional seals between it and the end walls of the vat circle. The present invention contemplates, therefore, that in practical installations, the aforesaid Vinflatable and deflatable membrane ,be confined endwise, more or less, to the axial dimension of the forming wire; and that beyond the ends of the inflatable and deflatable membrane, there be provided stationary non-dellatable, but resilient, seals which remain in constant sealing relationship between the movable and immovable parts of the apparatus, regardless of whether the aforesaid membrane is inflated or deflated. Such permanent seals, being beyond the ends of the forming wire, have no substantial effect upon the deposit of the stock upon the forming wire during conventional operation of the machine.

A practical embodiment of the invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a view in radial cross-section, somewhat schematic in form, of a typical cylinder mold and vat arrangement equipped for conversion, selectively, between the conventional and restricted or dry operation in accordance with the present invention;

FIGURE 2 is a sectional view taken along line 2-2 of the cylinder mold vat organization shown in FIG- URE l; v

FIGURE 3 is an enlarged sectional view taken along line 3-3 of FIGURE 2;

FIGURE 4 is a sectional view taken along line 44 of FIGURE 3, showing one form of sealing arrangement at the ends of the cylinder mold, and at the adjacent end i of the inflatable and deflatable envelope, as applied to one type of cylinder chime seal; and

v FIGURE 5 is a view corresponding to FIGURE 4, but showing the application of the invention to another form of chime seal.

Referring now to FIGURE l of the drawings, a typical cylinder mold type paper machine consists of a rotatable cylinder 1 mounted for rotation in the counterclockwise direction within a v'at 2. The outer periphery of the cylinder-1 is constituted of 4forming wire 3, and the interior wall 4 of the vat is substantially spaced from the forming wire 3-so as to confine a pool of paper stock which embraces a substantial part of, but less than all of, the periphery of the forming wire 3. The space 5 between the forming wire 3 and the interior vat wall 4 is herein referred to as the vat circle. At the upper extremity of the Vat circle on the side of the cylinder which is approaching the top in its rotation, there is provided a making board 6 over which paper stock is introduced to form the pool of stock in the vat circle and keep it replenished at the proper height. Suitable means, either gravity or suction or both, may be provided for inducing the iiow of white water from the pool of stock in the vat circle through the forming wi-re and into the interior of the cylinder from which it is drained in any suitable manner. At the top of the cylinder `1, there is provided a pickup felt 7 moving in substantial tangency with the forming wire for a short distance. The felt is pressed toward the forming wire by a couch roll l8, so that, as the felt 7 moves to the left, as seen in FIGURE 1, paper fibers, which have been laid `down on the forming wire 3 by the extraction of white water through the forming wire, are removed from the forming wire by the felt 7 and couch roll 8, so that as any increment of the forming wire rotates .counterclockwise beyond couch roll 8, it is substantially clear of paper fibers and ready to receive another deposit thereof when it enters the pool of stock maintained in the vat circle.y The arrangements described in this paragraph are typical of cylinder type paper machines, and form only background for the description of the present invention.

In accordance with the present invention, there is provided, at any selected location in the vat circle, a flexible and hermetically sealed envelope which, in this embodirnent of the invention, takes the form of a sheet of rubber 9 of a length (parallel to the axis of cylinder 1) substantially equal to the width (parallel to the axis of cylinder 1) of forming wire 3. The rubber sheet 9 is hermetically secured to the interior wall 4 of the vat in any suitable way so as to hermetically envelop an expansible yand contractible space of a magnitude such that it can be expanded so as to substantially bridge the space between the forming wire 3 and the interior wall 4 of the Vat.

In the embodiment shown, the upper edgeof sheet 9 is secured between a pair of clamps 10-11 which extend Afor the full length of sheet 9, and the lower edge of sheet 9 is secured between a pair of clamps 12-13 which likewise extend `for the full length of sheet 9. The respective clamps `1,0-111 and 1243 are drawn down sufficiently tight against the rubber sheet 9 so as to be in sealing relationship therewith, and may be secured in any suitable manner on the interior vat wall 4 at the chosen location.

In the embodiment shown, the iiexibily and hermetically enveloped space above mentioned is further enclosed at its ends by folding sheet 9 in the radial direction and thence back in the general direction of its length to a reentrant fold, as shown in IFIGURE 4, where the edges of the sheet 9 are engaged and clamped between plate 15 and rail 16,A as clearly shown in FIGURE 4, so as to seal the same together. KPlate 1S is preferably secured directly to the interior vat wall 4. While plate may, and preferably does, extend for the full length of rubber sheet 9, rails 16 are located only at the ends thereof. If desired, the rubber sheet 9, can be provided to overlie plate 15, i.e., be located on the interior of the enveloped space, but su-ch is not ordinarily necessary if the plate 15 is not pervious to fluid.

' Mounted on clamp '13, on the interior of rubber sheet 9, is a hinge 17, to the upper strap of which is connected .a plate 18, likewise on the interior of rubber sheet 9. The plate 18 extends subst-antially from end to end of the space which is hermetically enclosed by sheet 9. Plate 18 provides a firm support for the attachment on the exterior of sheet 9 of an apron 19. The apron 19 may be, and preferably is, a piece of rubber or rubber-like material substantially thicker than that of sheet 9. Apron '19 is secured las aforesaid on the exterior of sheet 9 by means of a clamping plate 2t) and a series of bolts 21. If desired, a further stiffening plate 22 may be provided between apron `19 and sheet 9, as shown in FIGUR-E 3. The plates 18 and 22 (if present) form a rigid portion in the envelope provided by sheet 9. Such a rigid portion is desirable in the mounting of apron 19.

As shown in FIGURE 3, plates 18 and 22 have their extremities remote from hinge 17 curved so as to permanently deiine a vertex of the triangular-shaped space enveloped by sheet 9. Apron 19 extends beyond the curved portion of plates 18 and 22, so as to provide a free end in cantilever relationship with the part of the apron which is held fast between plates 20 and 22 or `18. The free end 'of apron 19 may thus flex and conform itself to any irregularity in the forming wire 3 as the latter passes over the free end of the apron. The proportions of the parts just described are such that when they are in the position shown in FIGURE 3, i.e., distended, the free end of the apron will be maintained in substantial tangential sealing relationship with the forming wire 3 as the cylinder rotates.

Clamp 13 is provided with one or more apertures to accommodate a corresponding number of nipp-les 24. At one or more places lengthwise of sheet 9, clamp 12 is interrupted to accommodate a connecting flange 2S on eachV of nipples 24, and at such location or locations, ilange 25 serves the purpose of the interrupted clamp 12, yand the additional function of securing nipple 24 in her- -metically sealed relationshipv with sheet 9 so that the Inip-ple provides for fluid ingress and egress between the exterior and interior of the space hermetically confined by sheet 9. Aligned with each nipple 24, sheet 9 has a hole in it.

The one or more nipples 24 are connected by suitable pipefittings to a header 26 which may be located in any suitable position in the vat circle or in la vat sump, such as 27, where it does not interfere with the operation o-f the machine. The header 26 is preferably of a crosssectional area equal to the sum of the cross-sectional areas of all the nipples 24 which are provided. Under ordinary conditions, only one such nip-ple is necessary, provided its cross-sectional area is sufficient to enable it to pass the amount of fluid confined in the space enveloped by sheet 9 within a period of` time no greater than the minimum time within which it is desired that the diaphragm formed by sheet 9 move between fully distended and fully contracted positions.

The header 26 extends to the exterior of the vat, or to any other suitable drain, but if the header 27 does not extend to the exterior of the vat, it should be provided with a valve whose control does extend to the exterior of the vat. In the form shown in FIGURE 2, header 27 extends through the end wall of the vat to a valve 28, whose minimum orice, when fully opened, is governed by the same conditionsrecited above with respect to header 27. Valve 28 controls the flow of fluid between header 27 and drain. Between valve 28 and nipples 24, header 27 is provided with a standpipe 29 which may be, and preferably is, of much smaller diameter than that of header 27. Standpipe 29 extends upwardly to an elevation substantially 4above that of making board 6, so that, when filled, the hydrostatic column of fluid in header 27, and that within the space hermetically enveloped by rubber sheet 9, is greater than the possible hydrostatic head eX- 7 erted by the pool of stock in the vat circle upon the exterior of rubber sheet 9.

Alternatively, the valve^28 may be a three-way valve, so that when it is in the position where header 27 isconnected to drain, header 27 will be closed to sandpipe 29, and vice versa. In the arrangement shown in FIGURE 2, however, where valve 28 has no effect upon the connection between header 27 and standpipe 29, it is desirable that the portion of header 27 which extends between standpipe 29 and valve 28, as well as the valve itself and the drain pipe extending therefrom, have an orifice which is at least equal to the sum of the orifices in standpipe 29 and those in the nipples 24. Otherwise, in the forni shown in FIGURE 2, when valve 28 is opened to drain, it would not accommodate simultaneously both t-he ow from header 27 and the flow from standpipe 29. Such simultaneous accommodation is desirable in the interest of quick deflation of the space enveloped by sheet 9. On the other hand, it is sometimes desirable to provide for quick inflation of such space, and, in that event, the crosssectional area of standpipe 29 may be increased to equal, or nearly equal, that of header 27, but under such circumstances, it is desirable, as suggested above, to make valve 2S a three-way control.

As shown in FIGUR-E 2, standpipe 29 is provided at its top with a funnel 3G located beneath a dripping faucet 31, and at the -base of funnel 30, there is provided an outlet 32 from standpipe 29 to drain. Thus standpipe 29, once filled to the level of drain 32, is maintained filled to that level at all times, unless valve 28 be opened to drain.

' The construction at the opposite ends of the hermetically enveloped space, in the preferred embodiment, is illustrated in FIGURE 4. As stated above, the length of the hermetically enveloped space, or at least the length of the apron 19 associated therewith, is substantially the same as the axial dimension of the cylinder, or at least the forming wire thereon. Endwardly outward of the forming wire, the cylinder structure is usually provided withv an extension termed a chime, which is of lesser -radius than the forming wire 3, and is indicated at 33 in FIGURE 4. The chime 33 extends toward, but stops short of, the end wall of vat 2. Between the end wall of vat 2 and chime 33, there is frequently provided a collar, such as that shown at 34, so proportioned as to leave a slight space 35 between lthe stationary collar 34 and the rotating chime 33. About the chime 33 and collar 34, lthere is arranged, so as to bridge gap 35, a sealing belt which may take various forms. As shown in the drawings, the sealing belt 36 is of the garter strip type common in the art.

Since the function of diaphragm 9 when inflated, and its appurtenant apron 19, is to seal off the passage of paper stock in the clockwise direction (as shown in FIG- URE 1) beyond the location of the diaphragm and apron, and since the diaphragm 9 and its apron 19 terminate short of t-he end walls of vat 2, it is essential to provide an appropriate dam for blocking the flow of paper stock about the ends of diaphragm 9 and apron 19. In the form shown in the drawings, such a dam takes the form of a block 37 of porous or cellular rubber-like material which is tailor-made to fit the profile offered by the end of the cylinder, the end wall of the vat, and t-he intervening parts such as collar 34 and garter strip 36. Such a block may be either cast in situ or preformed to t the idiosyncrasies of any given machine. The block 37 may be made of foam rubber, or any suitable synthetic having, when cured, a substantial degree of resilience. Flexible polyurethane foam is ideal for the purpose. While FIGURE 4 of the drawings s-hows the block 37 at one end only of diaphragm 9, it will be understood that a comparable block is provided at the other end in order to seal the corresponding space thereat.

In FIGURE of the drawings, there is illustrated another form of stationary darn adjacent the end walls of the vat. In this embodiment, the cylinder is provided with a chime in the form of an annular angle bar 335, and the end wall of the vat is provided with a collar in the form of an annular angle bar 345, so disposed as to leave a small space 355 therebetween. An O-ring type of garter strip 365 bridges the gap 355. Flexible block 375 is provided for filling the space circumscribed by the wall of vat 2, diaphragm 9, apron 19, angle bar 335, garter strip 365, and angle bar 345. In the case of the type of garter strip shown in FIGURE 5, it is desirable, however, to relieve block 375 adjacent those quadrants of the garter strip which are nearest to space 355; and such relief is shown at 385.

In the operation of the method and apparatus hereinbefore described, it will be understood that, during operation of the machine as a conventional vat operation, the position of the diaphragm 9, and its adjunct parts, is such that apron 19 is completely free of contact with, and substantially spaced (in the radial direction) from, forming wire 3 so as to permit free flow of paper stock thereby in the clockwise direction, viewed from the longitudinal axes of the vat, and to permit such paper fibers as have been deposited upon the forming wire at positions clockwise (viewed from the longitudinal axes of the vat) of apron 19 to pass thereby on the wire without being contacted by the apron. The condition of the parts just described is herein termed the collapsed or deflated condition, and is illustrated generally by the dotted lines.

in FIGURE 3. When the parts are in the'collapsed position, they offer no substantial impediment to the flow of paper stock in the clockwise direction (viewed from the longitudinal axes of the vat) thereby, and provide no pockets for the accumulation of adventitious material which will prevent their free movement toward the position shown in full lines in FIGURE 3. When, during the conventional operation of the machine, it is desired to convert it to a dry or restricted vat operation, and thereby to vary the character of the paper being made, valve 28 is closed to shut off the access of fluid from standpipe 29 to drain through valve 28. Thereupon, the uid in standpipe 29 flows through header 27, and nipples 24 into the space enveloped by diaphragm 9. If quick operation is desired, faucet 31 may be opened to flow a full stream until the system refuses to take more fluid from faucet 31. The latter condition will be exhibited by overow through drain 32, and when such occurs (assuming faucet 31 will pass no more fluid than standpipe 29 will pass), diaphragm 29 will have been moved to its distended position shown in full lines in FIGURE 3, and apron 19 will have made contact with forming wire 3. When in this distended position, the arrangement of parts is such that no pockets are provided for the accumulation of adventitious material in positions where they will provide an impediment to subsequent movement of the parts to their collapsed position. Indeed, the V-shaped trough 39 between the free end of apron 19 and diaphragm 9 enlarges itself in moving from the operative to the collapsed position by virtue of the straightening of the free end of apron 19 in the process, and thereby loosens any deposit of adventitious material which may have accumulated therein during operation. When it is desired, during operation on a dry or restricted vat basis, to recouvert the machine into a conventional vat operation, all that need be done is to open valve 28, whereupon the fluid, which has been entrapped by diaphragm 9 and maintained under pressure of the hydrostatic head provided by standpipe 29, is immediately exhausted to drain so that diaphragm 9, and its adjunct parts, is forced to the collapsed position by the influence of the hydrostatic head of the pool of stock thereabove, aided by the action of gravity upon weight 23. Of course, if need should ever occur for instantaneous collapsing of the diaphragm, any suitable source of negative pressure can be applied to the discharge side of valve 28.

From the foregoing description, those skilled in the art should readily understand the structure and mode of operation of the apparatus disclosed andthe advantageous features of the method.v While one complete embodiment of the invention. has been described in detail, and various alternatives have been indicated, it is not to be understood that the invention is limited to the details hereinabove described or shown in the accompanying drawings. On the contrary, it is apparent that numerous modifications, variations, and adaptations will immediately Ioccur to those skilled in the art without departing from the spirit of the invention or the scope of the appended claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. A barrier for use between the forming wire and the Vat wall of a cylinder-type paper making machine comprising: a flexible diaphragm provided with an apron of flexible material which is substantially stiffer than said diaphragm, said apron having an end portion movable relative to said diaphragm and arranged to engage the forming wire, means for hermetically securing the margins of said diaphragm to the vat wall so as to envelop a space between the midsection of said diaphragm and said vat wall, fluid ingress and egress means for said enveloped space, and means associated with said fluid ingress and egress means for selectively controlling iluid pressure in said enveloped space.

2. A barrier for use between the `forming wire andthe vat wall of a cylinder-type paper making machine comprising: a flexible diaphragm provided with an apron of flexible material which is substantially stiffer than said diaphragm, said apron having an end portion movable.

relative to said diaphragm and arranged to engage the forming wire, means for hermetically securing the margins of said diaphragm to the vat wall so as to envelop a space between the midsection of said diaphragm and said vat wall,y part of diaphragm between said means for hermetically securing the margins of the diaphragm being provided with a relatively rigid reinforcement, said reinforcement being hinged relative to said wall, fluid ingress and egress means for said enveloped space, and means associated with said ingress and egress means for selectively controlling the iluid pressure in said enveloped space. v

3. A barrier for use between the forming wire and the vat wall of a cylinder-type paper making machine comprising: a flexible diaphragm provided with an apron of flexible material which is substantially stiffer than said diaphragm, said apron having an end portion movable relative to said diaphragm and arranged to engage the forming wire, means for hermetically securing the margins of the diaphragm to the vat wall so as envelop al reinforcement being biased toward the vat wall, fluid ingress'and egress means for said enveloped space, and means associated with said ingress and egress means for selectively controlling the uid pressure in said enveloped space.

4. A barrier for use between the forming wire and the vat wall of a cylinder-type paper making machine cornprising: a flexible diaphragm provided with an apron of flexible material which is substantially stiffer than said diaphragm, said apron having an end portion movable relative to said diaphragm and arranged to secure the forming wire, means for hermetically securing the margins of the diaphragm to the vat wall so as to envelop a space between the midsection of the diaphragm and the vat wall, a part of said diaphragm between said means for hermetically securing the margins `of the diaphragm being provided with a relatively rigid reinforcement, said reinforcement being hinged relative to said wall, the end of said hinged reinforcement remote from its hinge point l@ being curved toward the vat wall, fluid ingress and egress means for said enveloped space, and means associ-ated with said ingress :and egress means for selectively controlling the fluid pressure in said enveloped space.

5. A barrier for use between the forming wire and the vat wall of a cylinder-type paper making machine comprising: ia flexible diaphragm provided with an apron of flexible material which is substantially stiffer than said diaphragm, and having a terminal end portion divergent from said diaphragm, said end portion being movable relative to said diaphragm and arranged to engage the forming wire, means for hermetically securing the margins of the diaphragm to the vat wall so as to envelop a space between the midsection of the diaphragm and the vat wall, part of said diaphragm between said means for hermetically securing the margins of the diaphragm being provided with a relatively rigid reinforcement, said reinforcement being hinged relative to said wall and having an end thereof, remote from its hinge point, curved toward the vat wall, fluid ingress and egress means for said enveloped space, and means associated with said ingress and egress means for selectivity controlling the uid pressure in said enveloped space.

6. In a cylinder-type paper machine which is convertible from conventional vat operation to dry or restricted vat operation and vice versa, the combination of a ilexible diaphragm mounted and arranged to hermetically envelop a. space between the cylinder and the vat, said diaphragm extending substantially parallel with the axis of said cylinder and substantially from end to end of said cylinder, non-retractable sealing means bridging the space between the ends of said hermetrically enveloped space and the ends of the vat, and means for expanding and contracting the volume of said enveloped space.

7. In a cylinder-type paper machine which is convertible from conventional vat operation to dry or restricted vat operation and vice versa, said vat having a vat circle and end walls, the combination of a flexible diaphragm mounted 4and arranged to hermetically envelop a space between the cylinder and the vat, said diaphragm having end edges secured to the vat circle along said end walls at positions closer together on the vat circle than the overall longitudinal dimension of the diaphragm, and means acting on the interior of said diaphragm for forcing and retracting the midsection of said diaphragm -in the direction of said cylinder.

8. In a cylinder-type paper machine which is convertible from conventional vat operation to dry or restricted vat operation and vice versa, said vat having a vat circle and end walls, the combination of a flexible diaphragm mounted and arranged to hermetically envelop aspace between the cylinder and the vat, said diaphragm having end edges secured to the vat circle along said end walls at positions-closer together -on the vat circle than the overall longitudinal dimension o-f the diaphragm, and means -acting on the interior of said diaphragm for forcing and retracting the midsection of said diaphragm in the direction of said cylinder, said means being actuatable from the exterior of the vat.

9. In a cylinder-type paper machine which is convertible from conventional vat operation to dry or restricted vat operation and vice versa, said vat having a vat circle and end walls, the combination `of a flexible diaphragm mounted and arranged to hermetically envelop a space between the cylinder and the vat, said diaphragm lbeing provided with stiffening means extending over part of its surface, said diaphragm having end edges secured to the vat circle along said end walls at positions closer together to the vat circle than the overall longitudinal dimension of the diaphragm, and means acting on the interior of said diaphragm for forcing and retracting the midsection of said diaphragm in the direction of said cylinder.

10. A barrier for use between the forming wire and the vat wall of a cylinder-type paper making machine comprising: a flexible diaphragm provided with an apron of exible material which is substantially stiffer than said diaphragm, said apron having an end portion movable relative to said diaphragm and arranged to engage the forming Wire, means for hermetically securing the margins of the diaphragm to the vat wall so as to envelop a space between the midsection of the diaphragm and the vat wall, part of said diaphragm between said means for hermetically securing the margins of the diaphragm being provided with a reinforcement which is substantially stiffer than said diaphragm, uid ingress and egress means for said enveloped space, and means associated with said ingress and egress means for selectively controlling the fluid pressure in said enveloped space.

References Cited by the Examiner UNITED STATES PATENTS 7/1932 Parker 162-321 8/1932 Sundstrom et al. 162-335 12/1955 Hisey 162-347 3/1960 Western et al 162-347 4/ 1960 Goodwillie 162-347 11/ 1962 Collins 251-61 3/ 1965 Imbertson 611-30 FOREIGN PATENTS 1/1936 Austria. 3/ 1941 Great Britain.

15 DONALL H. SYLVESTER, Primary Examiner. 

1. A BARRIER FOR USE BETWEEN THE FORMING WIRE AND THE VAT WALL OF A CYLINDER-TYPE PAPER MAKING MACHINE COMPRISING: A FLEXIBLE DIAPHRAGM PROVIDED WITH AN APRON OF FLEXIBLE MATERIAL WHICH IS SUBSTANTIALLY STIFFER THAN SAID DIAPHRAGM, SAID APRON HAVING AN END PORTION MOVABLE RELATIVE TO SAID DIAPHRAGM AND ARRANGED TO ENGAGE THE FORMING WIRE, MEANS FOR HERMECTICALLY SECURING THE MARGINS OF SAID DIAPHRAGM TO THE VAT WILL SO AS TO ENVELOP A SPACE BETWEEN THE MISDECTION OF SAID DIAPHRAGM AND SAID VAT WALL, FLUID INGRESS AND EGRESS MEANS FOR SAID ENVELOPED SPACE, AND MEANS ASSOCIATED WITH SAID FLUID INGRESS AND EGRESS MEANS FOR SELECTIVELY CONTROLLING FLUID PRESSURE IN SAID ENVELOPED SPACE. 